JPH11281666A - Silicon acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform angular correction for aligning the oscillating direction of a sensor with the direction of input axis in the sensor without increasing manufacturing cost. SOLUTION: Bottom face of a package 3 containing a sensor chip 2 is set perpendicular to the acceleration input axis 11. A chip containing groove 3d is made in the sensor fixing face 3c in the package while inclining by an angle θagainst the sensor fixing face 3c such that a plane La including the center of gravity G of a hinge part 9 and a mass part 8 and intersecting the upper surface of an oscillatory substrate 4 at a microangle θ at the hinge part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon acceleration sensor and, more particularly, to a technology for mounting a sensor chip in a package such that a direction of a pendulum vibration centering on a hinge portion of a mass portion thereof coincides with an acceleration input axis. .

[0002]

2. Description of the Related Art A silicon acceleration sensor 1 has a sensor chip 2 mounted in a package 3 as shown in FIG. The sensor chip 2 includes a vibrating substrate 4, an upper stopper plate 5, and a lower stopper plate 6, as shown in FIGS. The vibration substrate 4 is made by etching a silicon substrate, and has an outer frame portion 7, a mass portion 8, and a hinge portion 9 that supports the mass portion 8 in the outer frame portion 7 in a cantilever manner.

The upper stopper plate 5 and the lower stopper plate 6 limit the magnitude of the pendulum vibration about the hinge part 9 of the mass part 8, and are fixed to the upper and lower surfaces of the outer frame part 7, respectively. 8 is mounted on a printed circuit board or the like such that the bottom surface of the package 3 is perpendicular to the acceleration input shaft 11. Assuming that a plane that includes the hinge part 9 and the center of gravity P of the mass part 8 and intersects the upper surface of the vibration substrate 4 and the hinge part 9 at a small angle θ is La, the plane La is perpendicular to the acceleration input shaft 11. Distributed to.

When an acceleration is applied to the sensor chip 2, the center of gravity P of the mass portion 8 oscillates with the hinge 9 as a fulcrum. When the plane La is arranged at right angles to the input shaft 11, the direction of the pendulum vibration coincides with the input axis direction, and accurate measurement is possible. A piezoresistive element is formed on the upper surface of the hinge part 9, and the acceleration is detected based on the amount of resistance change due to expansion and contraction.

As is apparent from FIG. 5, the input shaft 11 has an angle θ with respect to a center line Lb perpendicular to the plate surfaces of the vibration substrate 4, the upper stopper plate 5 and the lower stopper plate 6. When the sensor chip 2 is mounted on the package 3, the sensor chip 2 is generally mounted so that the plane La is perpendicular to the input shaft 11, in other words, the direction of the pendulum vibration of the center of gravity P coincides with the input axis direction. Can be Therefore, in the example of FIG. 8A, a wedge-shaped inclination correction plate 13 inclined by the angle θ is attached to the upper surface of the base 3a in the package 3, and the sensor chip 2 is attached thereon. In this manner, the inclination correction plate 13 corrects the vibration so that the vibration direction of the center of gravity P coincides with the input axis direction.

In the example of FIG. 6B, the sensor chip 2 is mounted on a flat mounting plate 14, and the mounting member 15 is tilted by the angle θ with respect to the plate surface of the package 3.
a, 15b so that the plane L
The angle “a” is perpendicular to the input shaft 11, so that the direction of the pendulum vibration of the center of gravity P matches the direction of the input shaft.

In FIGS. 8A and 8B, in order to correct the inclination θ of the plane La with respect to the upper surface of the vibrating substrate 4, that is, the deviation of the vibration direction of the sensor with respect to the input shaft perpendicular to the bottom surface of the package, the sensor chip 2 is moved by the angle θ. Although mounted on the package at an angle, the sensor chip may be mounted on the package without performing this correction. In this case, as shown in FIG. 9, when mounting the silicon acceleration sensor 1 on the printed circuit board 16 or the like, the silicon acceleration sensor 1 is soldered at an angle θ.

[0008]

In the conventional structure using the tilt correction plate 13 of FIG. 8A, the number of parts increases,
There is a problem that the man-hour for interposing the part increases and the manufacturing cost increases. FIG. 8B shows a conventional mounting plate 14 and mounting members 15a and 15b.
The same problem as described above occurs even in the structure using.

The conventional mounting method shown in FIG. 9 has a problem that the workability at the time of mounting the sensor is poor, the number of mounting steps is significantly increased, and accurate angle correction cannot be performed. An object of the present invention is to perform angle correction of a sensor vibration direction with respect to an input shaft inside a sensor without increasing manufacturing cost.

[0010]

(1) In the silicon acceleration sensor of the first aspect, the sensor chip is housed in a package. The sensor chip includes a vibrating substrate and an upper stopper plate and a lower stopper plate superimposed on and below the vibrating substrate.
The vibrating substrate is made by etching a silicon substrate, and has an outer frame portion, a mass portion, and a hinge portion which cantileverly supports the mass portion in the outer frame portion. The upper stopper plate and the lower stopper plate are fixed to the upper surface and the lower surface of the outer frame portion in order to limit the magnitude of the pendulum vibration about the hinge portion of the mass portion as a fulcrum.

In particular, the bottom surface of the package is perpendicular to the acceleration input shaft, includes the hinge portion and the center of gravity of the mass portion, and intersects the upper surface of the vibration board and the hinge portion at a small angle (θ). A chip housing groove that is inclined with respect to the sensor chip mounting surface by an angle equal to the angle (θ) is formed on the sensor chip mounting surface in the package so that the plane (La) to be formed is perpendicular to the acceleration input axis. .

(2) In the invention of claim 2, in the above (1), the package is a metal package with hermetic terminals.

[0013]

1 to 4 show an embodiment of the present invention.
The same reference numerals are given to portions corresponding to those in FIGS. 5 to 8, and redundant description will be omitted. In the present invention, the conventional FIG.
Similarly to the sensors A and B, the bottom surface of the package 3 is perpendicular to the input shaft 11. A plane La including the hinge portion 9 and the center of gravity P of the mass portion 8 and intersecting with the upper surface of the vibration substrate 4 at a small angle θ in the hinge portion 9 forms an acceleration input shaft 11.
Is formed on the sensor chip mounting surface 3c in the package so as to be at right angles to the mounting surface 3c by an angle equal to the angle θ, and the sensor chip 2 is attached to the groove 3d. . That is, the plane La is parallel to the sensor chip mounting surface 3c and the bottom surface of the package 3, and as a result, the plane La is perpendicular to the input shaft 11. Therefore, the direction 12 of the pendulum vibration about the hinge 9 of the center of gravity P of the mass portion 8 coincides with the direction of the input shaft 11.

The base 3a and the cap 3 of the package 3
b is made by molding a metal or resin, but can be easily coped with simply by providing a wedge-shaped projection for forming a chip housing groove 3d in a mold for molding the base 3a. Even if the storage groove 3d is provided, the manufacturing cost is hardly affected. 2 to 4, the base 3a of the package 3 is made of metal and has a plurality of hermetic terminals 22 embedded therein so as to penetrate inside and outside. These terminals and the connection terminals of the sensor chip 2 are wire-bonded.

[0015]

According to the present invention, the flat surface La can be easily adjusted by simply forming the chip housing groove 3d inclined by the angle θ on the sensor chip mounting surface 3c of the package 3.
1 to make the vibration direction of the sensor coincide with the direction of the input shaft. According to the present invention, a special mounting member as in the conventional example shown in FIG. 8 is not required in order to make the vibration direction of the sensor coincide with the direction of the input shaft. Therefore, those members and the number of mounting steps are reduced from the conventional cost. Yes, so there is no danger of increased manufacturing costs.

As in the conventional example shown in FIG. 9, a complicated angle adjustment when soldering the sensor 1 to the printed circuit board 16 is unnecessary.

[Brief description of the drawings]

FIG. 1 is a principle sectional view showing an embodiment of the present invention.

FIG. 2 is a partially exploded perspective view showing the embodiment of the present invention.

FIG. 3 is a perspective view showing a state where the sensor chip 2 is mounted on a base 3a of FIG. 2;

FIG. 4 is a perspective view showing the appearance of the sensor of FIG. 2 after assembly is completed.

FIG. 5 is a cross-sectional view of a conventional sensor and a sensor chip used in the sensor of the present invention.

FIG. 6 is a perspective view of the sensor chip of FIG. 5;

7 is a diagram showing the vibration substrate 4 and the lower stopper plate 6 of FIG.
The perspective view which shows the half part cut | disconnected by the a 'line.

FIG. 8 is a principle sectional view of a conventional silicon acceleration sensor in which the vibration direction of the sensor is angle-corrected inside the sensor so as to coincide with the direction of the acceleration input axis.

FIG. 9 illustrates a process for soldering a sensor to a printed circuit board.
FIG. 9 is a front view showing a mounted state of the silicon acceleration sensor in which the vibration direction of the sensor is angle-corrected so as to match the direction of the acceleration input axis.

Claims (2)

[Claims] 1. A sensor chip is accommodated in a package. The sensor chip includes a vibrating substrate and an upper stopper plate and a lower stopper plate superimposed on the vibrating substrate. The vibrating substrate is obtained by etching a silicon substrate. The outer frame portion, the mass portion, and a hinge portion for cantilevering and supporting the mass portion in the outer frame portion, the upper stopper plate and the lower stopper plate having the hinge portion of the mass portion as a fulcrum. In a silicon acceleration sensor fixed to an upper surface and a bottom surface of the outer frame portion to limit a magnitude of a pendulum vibration, a bottom surface of the package is perpendicular to an acceleration input axis; The center of the vibration substrate and the hinge section are crossed at a small angle (θ) at a small angle (θ) so that a plane (La) is perpendicular to the acceleration input axis. The Sachippu mounting surface, the silicon acceleration sensor, characterized in that inclined tip receiving groove with respect to angle equal to the angle (theta) the sensor chip mounting surface is formed. 2. The method according to claim 1, wherein the package is:
A silicon acceleration sensor, which is a metal package with hermetic terminals.